diff --git a/lib/sdk11/components/libraries/bootloader_dfu/bootloader.c b/lib/sdk11/components/libraries/bootloader_dfu/bootloader.c
index 1f423e6..9ca40e4 100644
--- a/lib/sdk11/components/libraries/bootloader_dfu/bootloader.c
+++ b/lib/sdk11/components/libraries/bootloader_dfu/bootloader.c
@@ -128,6 +128,9 @@ static void wait_for_events(void)
         // USB stack
         tusb_task();
 
+        // Send out cdc's data
+        tud_cdc_flush();
+
         if ((m_update_status == BOOTLOADER_COMPLETE) ||
             (m_update_status == BOOTLOADER_TIMEOUT)  ||
             (m_update_status == BOOTLOADER_RESET))
diff --git a/lib/tinyusb b/lib/tinyusb
index 5f1bec9..84ef486 160000
--- a/lib/tinyusb
+++ b/lib/tinyusb
@@ -1 +1 @@
-Subproject commit 5f1bec943b2a227d6b6f2188644c7641828787e7
+Subproject commit 84ef486418fe1d1e83217c8bdc55aaad2456a5fd
diff --git a/src/segger/nrf52840_bootloader.emProject b/src/segger/nrf52840_bootloader.emProject
index 7b54fe3..e1065e7 100644
--- a/src/segger/nrf52840_bootloader.emProject
+++ b/src/segger/nrf52840_bootloader.emProject
@@ -167,7 +167,7 @@
         </folder>
       </folder>
       <folder Name="tinyusb">
-        <folder Name="tinyusb">
+        <folder Name="src">
           <file file_name="../../lib/tinyusb/src/tusb.c" />
           <file file_name="../../lib/tinyusb/src/tusb.h" />
           <file file_name="../../lib/tinyusb/src/tusb_hal.h" />
diff --git a/src/usb/tusb_config.h b/src/usb/tusb_config.h
index d33efb8..88a4a97 100644
--- a/src/usb/tusb_config.h
+++ b/src/usb/tusb_config.h
@@ -75,11 +75,15 @@
  *------------------------------------------------------------------*/
 
 // FIFO size of CDC TX and RX
-#define CFG_TUD_CDC_BUFSIZE         1024
+#define CFG_TUD_CDC_RX_BUFSIZE      1024
+#define CFG_TUD_CDC_TX_BUFSIZE      1024
 
-// TX is sent automatically every Start of Frame event.
-// If not enabled, application must call tud_cdc_flush() periodically
-#define CFG_TUD_CDC_FLUSH_ON_SOF    1
+/* TX is sent automatically on every Start of Frame event ~ 1ms.
+ * If not enabled, application must call tud_cdc_flush() periodically
+ * Note: Enabled this could overflow device task, if it does, define
+ * CFG_TUD_TASK_QUEUE_SZ with large value
+ */
+#define CFG_TUD_CDC_FLUSH_ON_SOF    0
 
 // Number of supported Logical Unit Number
 #define CFG_TUD_MSC_MAXLUN          1